Plural rotary hydraulic apparatus



March 4, 1969 J. K. ADELMAN 3,430,574

PLURAL ROTARY HYDRAULIC APFARATUS Filed May 17,1967 Sheet of 2 FIG. 2

IN VE N TOR JOSEPH KALMAN ADE L MA /V By m, mew nut 6a A frorney 5 March 4, 1969 J. K. ADELMAN 3,430,514

PLURAL ROTARY HYDRAULIC APPARATUS Filed May 17, 1967 Sheet 3 of 2 W ,NVENTOR i JOSEPH KALMAN ADELMAN Byflhaay, & w 4 30 A rrorneys United States Patent 9 Claims ABSTRACT OF THE DISCLOSURE A pair of rotary vane pump units are slidably received in a cylindrical chamber in a pump housing, and are separated by an axially shiftable spacer having sealing and bearing surfaces. The housing includes a common inlet supplying both pumps, and tandem outlets each serving one pump and operable at different pressures. A pressure plate and a pressure ring are disposed in the chamber to the side of the pump units and are separated by a first pressure chamber communicating with one pump outlet. A second pressure chamber, communicating with the other pump outlet, is located at the outer surface of the pressure ring. The resultant loading force applied simultaneously to both pump units is proportional to the highest pump outlet pressure.

The present invention relates to plural rotary hydraulic apparatus and has for an object the provision of simple and effective structure for pressure loading a plurality of rotary hydraulic devices with a force always determined by the highest system pressure.

Pressure loading, or end loading, or rotary hydraulic devices such as fluid pumps and motors is a widely used method for providing a sealing force having a magnitude varying with the fluid pressure. For example, in the case of a rotary hydraulic pump, an end plate or bushing customarily is biased by pump outlet pressure into sealing engagement with the pump rotor and stator members. Advantages of this arrangement are that at lower pressures the problems of excessive friction are avoided, and at higher pressures the sealing force increases so that excessive leakage is prevented.

In plural pump or motor assemblies two or more rotary devices are associated with a single shaft, and may operate at different pressures. The usual method of pressure loading such assemblies is independently to seal each device with a force determined by the pressure associated with that device. However, this approach requires a complicated and inconvenient housing construction for isolating the pressure loading of the separate devices.

The present invention provides a simple arrangement wherein a plurality of rotary hydraulic devices are simultaneously pressure loaded with a force proportional to the highest pressure associated with any of the devices, regardless of which device is operating at the highest pressure. In addition, the novel arrangement of the present invention makes possible a simplified construction and also simplifies the assembly of the apparatus.

Briefly, a plural rotary hydraulic device constructed in accordance with the invention may include a housing having a generally cylindrical chamber. A pumping stack is slidably disposed in the chamber and includes a plurality of pump units separated by axially shiftable spacer means. A single compressive sealing or loading force is applied to the entire stack, and the magnitude of the loading force is proportional to the highest pump outlet pressure. In order to develop the pressure loading force, a plurality of piston members, one for each pump, are urged toward the stack. Each piston member is loaded with outlet pressure of the corresponding pump, and the resultant force applied to the stack is proportional only to the highest pressure.

Many objects and advantages of the present invention appear from the following detailed description of an illustrative embodiment of the invention, and in the course of this description reference is made to the accompanying drawings in which:

FIG. 1 is a sectional view of a dual vane pump assembly embodying the features of the present invention;

FIG. 2 is a sectional view of the apparatus of FIG. 1 taken along the line 2-2 of FIG. 1;

FIG. 3 is a sectional view of the apparatus of FIG. 1 taken along the line 3--3 of FIG. 1; and

FIG. 4 is a greatly enlarged fragmentary sectional view of a part of the apparatus of FIG. 1.

Referring now to the drawings there is illustrated a dual pump assembly constructed in accordance with the features of the present invention and designated as a whole by the reference numeral 10. The pump assembly 10 includes a housing generally designated as 12 within which is defined a generally cylindrical chamber 14. 'Within the chamber is disposed a stacked pumping arrangement generally designated as 16 and hereinafter sometimes referred to as a pumping stack. The pumping stack 16 includes a pair of rotary hydraulic pump units 18 separated by a spacer or divider plate 20.

In accordance with an important feature of the invention, and as described in greater detail hereinafter, the entire pumping stack 16 is pressure loaded with a force proportional to the outlet pressure of the pump unit 18 having the highest outlet pressure. A pressure loading arrangement designated as a whole by the reference number 22 is disposed in the chamber 14 and serves to develop the pressure loading force.

Referring now more specifically to the construction of the housing 12, the housing includes a generally cupshaped body 24 within which is disposed the housing chamber 14. The chamber is closed by means of a cover section 26 fastened to the body 24 by means of bolts 28. An operating shaft 30 extends through the chamber 14 in an axial direction and is rotatably journaled in bearings 32 and 34 associated with the body 24 and cover 26 respectively.

The pumping stack 16 including the pump units 18 and the spacer 20 is slidably received on the operating shaft 30 in the chamber 14, and one end of the pumping stack abuts a flat wall 26a of the cover section 26. The other end of the pumping stack 16 engages a flat surface 35a of a piston member or pressure plate 35 slidably received in the housing chamber 14. The ends of the pumping stack, comprising the outwardly directed faces of the pump units 18, are thus sandwiched between the interfacing flat surfaces 26a and 35a. The spacer 20 includes opposed flat surfaces 20a abutting the inwardly facing surfaces of the pump units 18.

Each pump unit 18 includes a rotor 36 having centrally directed teeth engaged with a splin'ed portion of the operating shaft 30. Thus the rotors 36 are mounted for rotation with the shaft and are slidable in an axial direction therealong. The rotors 36 are provided with a plurality of generally radially extending slots in which vanes 38 are reciprocally mounted. Each rotor 36 is surrounded by a stator in the form of a thrust ring 40 having a generally cylindrical outer wall slidably received in the housing chamber 14.

In order to reduce the bearing loads and provide a balanced pump, the pumping units 18 are of the radially balanced, double chamber type. Accordingly the thrust rings 40 include elliptically shaped inner bearing surfaces engaged by the outer edges of the vanes 38. As will be readily understood by those skilled in the art, upon rotation of the rotors 36 the vanes sweep the bearing surface of the thrust ring 40 and the regions between adjacent vanes 38 alternately expand and contract in volume to produce a pumping action.

Fluids flows through the assembly between an inlet port 42 (FIG. 1) common to both pump units 18 and a pair of outlet ports 44 and 46 in the body 24 and cover section 26 respectively. Each outlet port receives fluid from one of the pump units 18, and the outlet ports 44 and 46 may serve independent hydraulic circuits having different pressure requirements. Accordingly, the outlet fluid pressure of the pump units 18 may differ.

Inlet fluid from the inlet port 42 communicates with one side of the pumping stack 16 at a recess 48 (FIGS. 1 and 3) opening directly onto the housing chamber 14. Fluid also communicates with the opposite side of the stack at a recess 50 (FIGS. 1 and 3) extending in an axial direction along the periphery of the chamber 14. The recesses 48 and 50 are in continuous communication by virtue of peripheral grooves 52 encircling the chamber 14 (FIG. 2).

From the recesses 48 and 50, fluid is introduced into the inlet zones of the pump units 18 by a system of inlet passages associated with the cover section 26, the spacer 20 and the pressure plate 35. The cover section 26 includes a pair of inlet passages 54 and 56 communicating with the inlet zone between the rotor 36 and the thrust ring 40 of one pump unit 18 (see FIGS. 1 and 3). Similarly, the pressure plate 35 includes a pair of inlet passages 58 and 60. The spacer 20 includes inlet passages 62 and 64 communicating with one of the pump units 18, and inlet passages 66 and 68 communicating with the other pump unit 18. In order to balance the pressures acting on the vanes 38, each inlet passage includes an extension communicating with the inner edge of the vanes.

Pressurized outlet fluid is conducted from one of the pump units 18 to the outlet port 44 by way of a recess 70 in the cover section 26. A pair of outlet passages 72 and 74 extend from the recess 70 to the face 26a of the cover section, and communicate with the high pressure zones of the pumping region defined between the rotor 36 and thrust ring 40 (FIGS. 2 and 3). In order to balance the forces acting on the vanes 38, the passages 72 and 74 include extensions communicating with the inner surfaces of the vanes. In addition, the spacer 20 is provided with complementary passages 76 and 78 communicating with the high pressure zones and the inner surfaces of the vanes.

Pressurized fluid is conducted from the other pump unit 18 to the outlet port 46 by way of a pressure chamber 80 defined between the pressure plate 35 and a piston member or pressure ring 82. Outlet passages 84 and 86 extend from the high pressure zones of the unit 18 through the pressure plate 35 to the chamber 80. Extensions of the passages 84 and 86 communicate with the inner edges of the vanes, and complementary passages 88 and 90 are provided in the spacer 20.

In accordance with an important feature of the present invention, the entire pumping stack 16, and thus each end of the pumping units 18, is pressure loaded with a single loading or sealing force proportional to the highest of the two outlet pressures. In the illustrated embodiment of the invention, the sealing force is provided by the pressure loading arrangement generally designated as 22, and including the pressure plate 35 and the pressure ring 82.

In order to develop the pressure loading force, pressure fluid from one of the pumping units 18 is communicated with the chamber 80 between the pressure plate 35 and the pressure ring 82 as described previously. Pressure fluid from the other pumping unit 18 is conducted from the recess 70 by way of a conduit 92 to a pressure chamber 94 disposed between the pressure ring 82 and the body 24. The pressure chambers 80 and 94 have equal eflective areas.

The construction and operation of the pressure loading arrangement 22 can best be seen by reference to FIG. 4.

As there illustrated, the pressure fluid from one of the pump units 18, designated as P operates within the chamber and biases the pressure plate 35 toward the pumping stack 16, and also biases the pressure ring 82 away from the pump stack. Pressure fluid from the other pump unit 18, designated as P operates within the pressure chamber 94 and biases the pressure ring 82 against the pressure plate 35 and toward the pumping stack 16.

In operation, assume first that P is at a low value substantially equal to zero and P is at a higher value. In this condition, the pressure exerted by the fluid in the chamber 94 biases the pressure ring 82 and the pressure plate 35 toward the left, as viewed in FIG. 4, and applies a compressive sealing force or loading force to the entire pumping stack 16. Since all of the elements of the pumping stack including the pump units 18 and the spacer 20 are axially slidably mounted in the housing chamber 14, the loading force applied by the pressure plate 35 provides a sealing force at both side faces of each of the pumping units. This sealing force, since it is determined by the high outlet pressure P simultaneously loads both pumping units sufliciently to prevent substantial leakage in the pumping unit 18 developing the pressure P Assume now that the pressure P is very low or approximately zero and the pressure P is substantially higher. In this condition the pressure acting in the chamber 80 biases the pressure plate 35 against the pumping stack 16 to apply a compressive sealing or loading force to each of the pump units 18. Thus there is provided a sealing force, determined by the pressure P effective at the side faces of both pump units and suflicient to prevent substantial leakage of fluid from the pump developing the pressure P If both pump outlet pressures are at substantial values, the resultant compressive sealing force applied to the pumping stack 14 is always determined by the pump outlet pressure having the highest value. For example, if P and P are equal, the forces acting on both sides of the pressure ring 82 balance one another out, and the force acting in the chamber 80 on the pressure plate 35 biases the plate against the pumping stack 16. Thus the loading force is the same as if one or the other of the pressures were zero. Similarly, if P exceeds P the value of the pressure P determines the loading force, and conversely if P exceeds P the value of the pressure P determines the loading force.

From the above it can be seen that the pressure loading force or sealing force applied to the pumping stack 16 is always proportional only to the pressure of the pump outlet fluid having the highest pressure, regardless of which of the pump units 18 is operating at the highest pressure. Accordingly it can be seen that a simplified and straightforward arrangement is provided by the present invention for simultaneously pressure loading a plurality of pumps in a plural rotary hydraulic device.

Since the entire pumping stack 16 is axially slidable in the housing chamber 14, the construction of the assembly 10 is simplified, as compared to known plural pump arrangements having more complex housing constructions. Assembly of the various parts is simplified because the various elements are merely inserted into the chamber 14.

Although the present invention has been described with reference to a dual vane pump arrangement, the features of the invention could also be applied, for example, to gear pumps. In addition, the features of the invention are applicable to hydraulic motors as well as hydraulic pumps, in which case the high pressure fluid used for pressure loading the hydraulic devices would be the inlet fluid rather than the outlet fluid.

The embodiment of the invention illustrated and described herein includes a pair of pump units. However, the features of the invention could be extended to apply to arrangements including more than two units. For example, the pumping stack 16 could be enlarged to include three or four or more pump units 18 separated by spacer elements. In this case, the number of piston-like pressure plates or pressure rings would be increased, and the back side of each plate or ring would be provided with a pressure chamber communicating with the outlet pressure of one of the pumps. The novel result produced by the present invention would be accomplished with such an arrangement, i.e., the pressure loading or sealing force applied to the pumping stack would always be determined by the outlet pressure of the pump having the highest outlet pressure.

While the present invention has been described in connection with the details of a particular embodiment there of, those skilled in the art may devise other modifications and embodiments falling within the scope of this invention. Accordingly, details of the illustrated embodiment are not intended to limit the invention except insofar as set forth in the accompanying claims.

What is claimed as new and desired to be secured by Letters Patent of the United States is:

1. A plural rotary hydraulic assembly of the pressure loaded type comprising:

a housing having a chamber therein;

a pumping stack disposed in said chamber and arranged for axial movement therein; said pumping stack including a plurality of pumping units each including a rotor assembly and a stator assembly defining a pumping chamber therebetween;

said pumping stack also including sealing means disposed between adjacent pumping units;

inlet means for introducing low pressure fluid to the pumping chambers of said pumping units;

an outlet passage associated with each pumping unit for conducting high pressure fluid therefrom;

and pressure loading means for applying a compressive sealing force to the entire pumping stack in accordance with the highest outlet pressure of said pumping units;

said pressure loading means comprising a plurality of piston elements disposed in said chamber, one corresponding to each of said pumping units;

all of said piston elements being disposed at one side of said pumping stack;

means defining a pressure region at the side of each piston opposite the pumping stack;

and means communicating each pressure region with the outlet passage of the corresponding pumping unit.

2. A dual hydraulic apparatus comprising a housing having a chamber therein, said chamber having an end Wall, a shaft extending into said chamber in an axial direction, a hydraulic assembly slidable along said shaft in said chamber and abutting said end Wall, said hydraulic assembly including a pair of rotary hydraulic units and a spacer plate between said units, said units and said spacer plate having interfacing sealing and bearing surfaces, low pressure passage means in communication with low pressure zones in said units, a pair of high pressure passages each communicating with a high pressure zone in only one of said units, a first end loading member abutting the end of said hydraulic assembly opposite said end wall, a second end loading member abutting said first end loading member, a first pressure chamber between said first and second end loading members, a second pressure chamber at the outer surface of said second end loading member, and means continuously communicating one of said high pressure passages with said first pressure chamber and continuously communicating the other high pressure passage with the second pressure chamber.

3. The dual hydraulic device of claim 2, said rotary hydraulic units comprising vane pumps.

4. A plural rotary hydraulic apparatus of the pressure loaded type comprising a housing, a chamber in the housing, a stacked assembly slidably received in said chamber and including a pair of rotary pump units and a spacer between said pump units, said spacer having opposed sealing and bearing surfaces abutting side faces of said pump units, a pair of outlet passages communicating with said pump units and each receiving pressurized fluid from one of said pump units, a piston element in said chamber operatively connected to said stacked assembly for applying a compressive loading force thereto, means defining a pressure region adjacent said piston element in communication with one of said outlet passages for biasing said piston element toward said stacked assembly with a force determined by the outlet pressure of one of said pump units, and additional loading means acting against said piston element to increase the loading force when the outlet pressure of the other pump unit exceeds the outlet pressure of said one pump unit.

5. The apparatus of claim 4, said additional loading means comprising a second piston element acting against said first piston element, said pressure region being located between the efirst and second piston elements, and a second pressure region adjacent said second piston element in communication with the other outlet passage for biasing said second piston element toward the first piston element with a force determined by the outlet pressure of said other pump.

6. A dual pump apparatus comprising a housing having a chamber therein, a pumping assembly in said chamber, said pumping assembly including a pair of pump units and an axially shiftable spacer plate between said units, said pump units and said spacer plate having interfacing sealing and bearing surfaces, inlet passage means for introducing fluid to said pump units, first and second outlet passages each communicating with only one pump unit for conducting outlet fiuid therefrom at an increased pressure, first and second end loading members acting against an end of said pumping assembly, a first pressure chamber at the side of said first end loading member opposite said pumping assembly, a second pressure chamber at the side of said second end loading member opposite said pumping assembly, and means continuously communicating said first outlet passage with said first pressure chamber and continuously communicating said second outlet passage with the second pressure chamber.

7. A dual pump assembly as claimed in claim '6, said first and second pressure chambers having equal effective areas.

8. A dual pump assembly as claimed in claim 7, said second end loading member being disposed between said first and second pressure chambers so that said second end loading member is biased toward said pumping assembly only when the pressure in said second pressure chamber exceeds the pressure in said first pressure chamber.

9. A dual pump assembly as claimed in claim 8, said pump units each including a vane-carrying rotor, and a stator member surrounding said rotor and defining inlet and outlet zones within said stator.

References Cited UNITED STATES PATENTS 2,845,873 8/1958 Lapsley 230-158 X 3,204,565 9/1965 Kirkpatrick 103-136 3,223,044 12/1965 Adams et al. 3,272,130 9/ 1966 Mosbacher 103-5 JAMES W. WESTHAVER, Primary Examiner.

US. Cl. X.R. 

